/* 

  Bubble sort in Picat.

  Inspired by the SETL procedure in
  http://www.settheory.com/Chapters/Chapter_4.html

  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


% import util.
% import cp.


main => go.


go =>
  _ = random2(),
  T2 = [random(1,300) : _ in 1..300],
  T2 := bubble_sort(T2),
  print(T2),
  nl.



bubble_sort(T) = Ret =>
  T2 = copy_term(T),
  Len = T.length,
  Check = true,
  while(Check = true)
    Swapped = false,
    foreach(I in 2..Len)
      if T2[I-1] > T2[I] then
        T2 := swap(T2,I-1,I),
        Swapped := true % interchange the items.
      end
    end,
    if Swapped = false then
      Check := false
    end
  end,
  Ret = T2.


%
% Swap position I <=> J in list L
%
swap(L,I,J) = L2, list(L) =>
  L2 = copy_term(L),
  T = L2[I],
  L2[I] := L2[J],
  L2[J] := T.